Electromagnetic horn



Sept. 22, 1936. R. M. CRITCHFIELD 2,055,376

ELECTROMAGNETIC HORN Filed Aug. 5, 1927 2 Sheets-Sheet 1 Sept. 22, 1936. R. M. CRITCHFIELD ELECTROMAGNETIC HORN Filed Aug. 5, 1927 2 Sheets-Sheet 2 H r l v I Patented Sept. 22, 1936 UNITED STATES ELECTROMAGNETIC HORN Robert M. Oritchfield,

by mesne assignment Anderson, Ind., assignor, s, to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application August 5, 1927, Serial No. 210,879

4 Claims.

This invention relates to improvements in sound signalling devices particularly adaptable for use on motor driven vehicles.

It is among the objects of the present invention to provide a sound signalling device, or horn,

of simple structure and design, which may be produced cheaply and with a minimum expenditure of labor.

Another object is to provide a horn which may be adjusted to regulate the quality and intensity of the sound produced without disturbing the adjustment of any other portion of the mechanism.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompany ing drawings wherein a preferred embodiment of one form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a rear end view of the signalling device, the cover being shown in section in order to disclose the interior mechanism;

Fig. 2 is a sectional view taken along the line 2-2 of Fig. 1, certain parts however being shown 5 in elevation for the sake of clearness;

Fig. 3 is a fragmentary view showing in elevation certain parts illustrated in section in Fig. 2;

Fig. 4 is a fragmentary sectional view taken along the line 4-4 of Fig. 1;

30 Fig. 5 is a detail plan view of the movable contact element;

Fig. 6 is a section taken along the line 6-6 of Fig. 5;

Fig. 7 is a detail view of the stationary contact 35 bracket;

Fig. 8 is a plan view of the field frame of the electro magnetic motor;

Fig. 9 is a section taken along the line 9-9 of Fig. 8;

40 Fig. 10 is an end view of the field frame;

Fig. 11 is a perspective view of the field frame with one end plate detached to show its conformation;

Fig. 12 is a view similar to Fig. 8, however, show- 45 ing the windings in place in the frame;

Fig. 13 is a side view of Fig. 12, a part section being taken along the line l3l3 of Fig. 12; and

Fig. 14 is a perspective view of coil retaining clip, ready for insertion between the coil and 50 field frame after which one end may be bent over as indicated in dotted lines.

Referring to the drawings, the numeral 29 designates a base, cup-shaped, upon which is supported the operating mechanism of the horn.

55 The bottom of the cup-shaped base is termed the main mounting platform and is designated in Fig. 4 by the numeral 2|. This bottom is apertured, the metal punched out of the bottom to form the aperture being bent up to provide a bracket 22 having a portion 23 parallel with but 5 spaced from the main mounting platform 2|. Another bracket 24 formed from the material punched out of the bottom to form the aperture, provides a bracket 24 diametrically opposite the bracket 22. The base is provided with an out- 10 wardly extending annular flange 25, having a plurality of apertures for receiving screws 26 which pass through apertures in flange 27 of the sound projector 28 to secure said sound projector to the base. A diaphragm 29 is interposed between the 5 flanges 2'! and of the projector and base respectively and is clamped therebetween by means of screws 26, thus providing a yieldable partition between the base and the sound projector.

Upon the parallel portion 23 of the bracket 22 20 there is secured one end of a blade spring 30 which extends toward the axis of the base parallel with the main mounting platform 2|. The contacts of the interrupter mechanism or circuit controller are insulatingly mounted on this portion 25 23 of the bracket 22.

In Figs. 5 and 6 the movable contact member of the circuit controller is clearly illustrated. The resilient plate 3| has a foot portion adapted to be secured insulatingly to the bracket while 30 the free end of said plate is provided with a cage member 32 retaining an insulating block 33 in position on the plate. Contact element 34 is used to rivet the cage 32 to the plate 3|. Fig. '7 illustrates the stationary contact plate 35 provided 35 with the stationary contact member 36 which is adapted to be engaged by the movable contact member 34. Screws 31 together with insulating washers maintain the contact arms 35 and 3| insulatingly on the bracket 22. An angular bracket 38 is secured to the free end of the blade spring 30 and has an adjustable screw 39 supported in its free end, said screw being adapted to engage the insulating member 33 carried on the movable contact arm 3| to open said contacts, as will be explained hereinafter. A rod 40 is secured to the free end of the blade spring 30 and extends toward the diaphragm, being secured to said diaphragm by means of clamping collars 4| and 42 pressed against opposite sides of the diaphragm by means of a nut 43 provided at the end of the rod 40, which nut also holds the tone modifying disc 44 in position on the rod and in front of the diaphragm 29. An armature 45 is carried on the rod 40 adjacent the free end of spring 30, said armature being maintained in normal position by the spring 30 and the diaphragm 29.

The armature 45 is reciprocated by means of an electro-magnet comprising a field frame 5% which is adjustably supported on the mounting platform 2! of the .base. The field frame comprises a plurality of E-shaped magnetic plates 5i riveted together, the E-shaped plates forming parallel grooves 52 and 53 into which a field winding 5 is adapted to be placed. The end plates 55 and 56 of the field frame are provided with angular shelf portions 51 and 58 respectively, said portions being apertured as at 59 and 69 respectively to permit insertion of the field winding 54 into 7 the grooves 52 and 53. The shelf 57 is provided with a central aperture (it, while the shelf 58 has two such apertures 62 and 63, spaced on opposite sides of the center. A central aperture 64 is provided in the field frame for purposes to be described.

The field winding 54 is wound ordinarily with tape about which is placed a winding guard 65, said guard fitting into the grooves and against the end plates so as to reduce the possibility of short circuit at these points. A plate 66 is inserted between the ends of the field winding and the end plates 55 and 56, one end of said plates being bent over the field winding as at 61, the other over the field frame as at 68 for purposes of retaining the field winding in the grooves '52 and 53.

In Fig. 4 the mounting platform 2! is shown provided with screw threaded studs it having nuts H and 72 provided thereon. V The nuts 12 are first removed and the, field frame is 'then placed in position so that the studs enter the apertures iii, 62 and 63, the shelf portions El and 58 resting upon the nuts ll, after which nuts 12 are placed upon the structure to clamp the shelves securely in position on said studs.

Whenit is discovered that the gap between the pole piece faces of the field frame is too great, then the nuts 72 may be loosened and the nuts "H screwed upwardly as regards Fig. 2 until the proper gap between the armature and the field frame is obtained, at which time nuts 72 may be tightened. From this it may be seen that the field frame is supported adjustably upon the mounting platform independently of any other portion of the operating mechanism. The contacts 34 and 36 may be adjusted relative to each other by the operation of screws 39 and 35a respectively.

The energization of the field frame or electromagnet attracts the armature against the effect of thespring 3i? and the diaphragm 29, thus moving'said armature toward the field frame and consequently flexing the diaphragm outwardly toward the projector 28. This movement of the armature will cause the screw 39 to move the contact arm 3! and consequently the contact 34 out of engagement with the contact as, breaking the circuit, thus permitting the spring 38 and diaphragm 29 to return to normal position and again closing of the contacts 34 and 36. If it is desired to flex the diaphragm a greater extent in order to obtain a tone of greater intensity, or perhaps better quality, the field frame is moved away from the armature by operating the nuts H and 12 down toward the mounting platform 2|. This adjustment of the field frame does in no way affect the adjustment of the interrupter mechnism nor any initial adjustment of the diaphragm.

The present structure provides a field frame for the electro-magnetic motor which is easily assembled and then placed in position in the horn,

a minimum expenditure of material and labor being necessary to produce the device.

While the form of embodiment of the present invention constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the-scope of the claims which follow.

What is claimed is as follows:

1. In a sound signal the combination comprisingya magnet frame having channels, a field coil located within the channels; and means to retain the coil within the channels, said means comprising, a member extending between the frame and coil and having a part bent over the side of the frame remote from the coil, and having a part engaging the outer side of the coil.

2. In a sounding signal, a magnet motor comprising in combination, a plurality of 'E-shaped magnetic plates, end plates arranged at either end of said magnetic plates, and means riveting all of said plates into a compact unit, said end plates providing angular shelf portions bent into a plane substantially flush with the notched side edges of said magnetic plates, said shelf portions being apertured so as to allow for the passage of a field winding therethrough, a field winding disposed in the notches of said magnetic plates and lying beneath the face of said shelf portions; and substantially Z-shaped retaining plates between the winding and frame for securing said field winding in the recesses provided by said magnetic and end plates, the ends of said retaining plate being hooked behind the winding and I end plates respectively.

3. In a sound signal the combination comprising, a magnet frame having parallel grooves on one side thereof a field coil having portions located within the grooves; and means to retain the coil within the grooves and comprising, a member passing between the coil and frame and hooked, behind the magnet frame on the side opposite the grooves and having a part engaging the side of the coil opposite the grooves.

4. In 'a sound signal the combination comprising, a magnet frame having channels, a field coil located within the channels, and means to retain the coil within the channels, said means comprising bendable clips interposed between the coil and frame and having portions hooked over the frame, and other portions reversely hooked over the coil so as to retain the coil within the channels of the frame.

ROBERT M. CRITCHFIELD. 

